Parents who 'engage in conversation' with their babies can help improve their language development faster than simply talking when they are in the room.

Researchers from Stanford University and others studied the brains of babies aged between five and eight months while they slept inside an MRI machine.

Rather than simply overhearing adult words, parents who take it in turns to have 'conversations' with their babies can shape their future language abilities, they found.

Scientists say that the brain's language networks may develop in two stages - in the womb they develop processing networks to process sound, then another network once they are a few months old to understand more complex language.   

The amount and quality of the language babies are exposed to has a significant affect on their future language abilities, lead author Lucy King wrote.